Safety starter circuit and unit



l. S. JACOBSEN Dec. 27, 1949 Filed June 21, 1947 SAFETY STARTER CIRCUITAND UNIT 2 Sheets-Sheet l L|NE VOLTAGE ATTO R N EYS l. S. JACOBSENSAFETY STARTER CIRCUIT AND UNIT Dec. 27, 1949 Filed June 2l, 1947 2Sheets--SheeiI 2 Patented Dec. 27, 1949 UNITED STATES PATENT OFFICEIndustrial Electronics Corporation,

Newark,

N. J., a corporation of New Jersey Application June 21, 1947, Serial No.756,186

Claims. 1

The present invention is concerned with safety starting units and withcircuits incorporating the same for the protection of gaseous,electrical discharge devices such as fluorescent lamps of the hotcathode type.

It is among the objects of the invention to provide a unit of the abovetype which is relatively inexpensive, compact and economical inoperation, requiring a minimum of parts and which lends itself for usewith fluorescent lamps and the conventional xtures thereof as areplacement for glow starters of conventional type, which does not drawcurrent when the lamp is functioning normally and which assures theprompt elimination of the intermittent flashing on and off of adefective lamp, regardless of reasonable variations in ambienttemperature, thereby not only avoiding the annoyance of such hashing butalso safeguarding the starter unit itself from the destructive effect ofsuch intermittent starting.

Another object is to provide a safety circuit for a starter unit of theabove type which operates dependably and promptly to preclude theapplication of starting current to a defective lamp, and to maintain thelamp from flashing after the first few starting impulses have beenapplied thereto, regardless of normal variations in ambient temperatureand which automatically restores itself promptly to permit normaloperation of a new lamp substituted for the defective one.

A feature of the invention is a heat responsive switch arm connected atone end in circuit between a control resistor and a safety resistor, thepair of resistors being placed in series with each other and with a glowswitch starter, the electrodes of a gaseous electric discharge deviceand a ballast coil. In a preferred embodiment shown, the switch armshort circuits the safety resistor from the circuit, both when the lampis operating normally and when the circuit is not energized, thatresistor functioning only with a defective lamp. In response to aprolonged starting current through the control resistor caused byrepeated attempts to start a defective lamp, the switch arm isdisplaced, thus removing the short circuit from the safety resistor tobring it into action at such time only. The heating effect of the safetyresistor will thereupon positively move the switch arm without oatingthereof until it short circuits the glow switch and the control resistoreffectively to remove them .from the circuit. Continued current passingthrough the safety resistor which is preferably of high ohmicresistance, produces sufficient heat to retain the switch arm indeflected position and thus retain the short circuitA across the glowswitch until the circuit is broken, thereby preventing the glow switchstarter from starting or attempting'to start the fluorescent lamp.

In the accompanying drawings in which are shown one or more of variouspossible embodiments of the several features of the invention:

Fig. 1 is a circuit diagram showing an embodiment of the safety startercircuit,

Fig. 2 is a front elevational view of the starter unit showing only thecasing in cross section,

Fig. 3 is a side elevational View, similar to Fig. 2,

Fig. 4 is a rear elevational View similar to Fig. 2,

Fig. 5 is a transverse cross sectional View taken along line 5-5 of Fig.4, and

Fig. 6 is a view similar to Fig. 5 taken along line 6-6 of Fig. 4.

Referring now to the drawings, there is shown in the diagrammatic viewof Fig. .1. a conventional gaseous electric discharge device I0 of thehot cathode type such as a iiuorescent lamp including a pair ofelectrodes II and I2 at opposite ends thereof. One of the mains I3connected to electrode II has a ballast coil I4 in series therewith,while a switch I5 is shown in the other main I6, the latter beingconnected to electrode I2.

The starting circuit includes terminals 22 and 23 which are connected toelectrodes il and I2 respectively of the lamp by leads I'I and I8. Astarter I9 which preferably is of the glow switch type has one of itselectrodes 3I connected to terminal 22 and the other electrode 3!!thereof to lead 44 of control resistor 43, the other lead IIB of whichis connected to lead All of resistor 39, the other lead 4I oi whichilatter resistor is connected to terminal 23. Thus starter I3, resistor43 and resistor 39 are connected in series between terminals 22 and 23.The xed end of a bi-metallic switch arm 32 is connected as shown betweenresistors 43 and 39, for its free end to be movable between the contactends of contact leads 36 and 31, respectively, connected to contacts 22and 23. The free end 35' of switch arm 32 normally engages the contactend of lead 3l, so that resistor 39 is normally short circuited.

When switch I5 is closed, the'line voltage will be applied across theelectrodes II and I2 of the lamp and across terminals 22 and 23. As theapplied voltage is at the outset insufficient to cause arcing of thelamp I0 but sufficient to cause glow switch starter I9 to ionize,current will ow through the circuit, establishing a magnetic neld in theballast coil Ill, the collapse of which upon opening the circuitestablishes the desired Voltage. The path of current through the circuitwill be through main I 6, electrode I2, lead I8, terminal 23, contactarm 31, switch arm 32, lead fifi, resistor 43, lead 44 ,through theglowswitch .starter I9, terminal l'22, lead I'I,electrode `I I, ballast:coil I4 and main I3. The heat developed by the ionization of the glowswitch I9 will bring the contacts 30, 3| thereof together and close thegap therebetween, thereby stopping the glow. As soon as the glow ceases,the bimetallic contact v3l in the glow switch will cool and deflect,thereby causing the contacts of the glow switch to separate. This willbreak the starting circuit through the electrodes II and I2 and theballastcoil I4, causing the magnetic collapse and producing .the voltageto discharge through the circuit. AThis sudden impulse should -bridgethe gap between the now heated electrodes `in 1the lamp `and 4start thearc, 'causing the Alamp to flight. Since the arc when once maintainedrequires voltage fless than 'that required vto @initiate Athe -glowdischarge Ain 'the glow switch, the latter Awill 4remain out of actionandthe starting circuit is broken due to the gap between'the-'contacts'38, '3l of glow switch 19. If jthe lamp is -in lvnormal condition, oneor twocyc'les of the-glow switch fshould Ylight it.

At the same time ythat 'lthe `contacts 39, 'Irl of the glow switch are-cl'osed but before the lam-p .lighfts, heatis generatedlin1resistor243which will be idissipatedito the bimetallic switch arm '32. IIf=thela'mp is defective, continuedfcyclesof :the .glow switch I9 willproduce suiicient heat in the resistor =1l-3to causeswtc'h farm '32 todeect `tothe position indicated in dashes in Fig. l so that the :end 35flthereof `iis moved .outfof .engagement with the contact 3l, therebyremoving the sho'r't circuit about `resistor 39. That .resistor will'fnow draw current, the circuit being through main IB, elec- .trode I2,lead I8, terminal 2.3, lead ^4'I, resistor 39, leads 4D and :46,resistor 43,.lead 44,glow switch .'-IfSiwhich is ionized, 'terminal'22,1lead I l; electrode "IfI, ballast coil I4 fand mai'n '-I3. VThecombined heat from resistors .39 and 4'3 will rcause lswitch arm-32 Ctobe positively :deilected '.until iit :is *brought intov engagement' with:contact 36 A as shown in dot and dash lines 'in "Fig, 1, land i'shortcircuit glow switch :I9 rand 1resistor 43, fth'ereby v'effectively'removing them from the circuit and thus placing resistor *se-directlyacross'flamp electrodes II and I2. Continued `passage ofcurrent `through lresistor`39 will produce sufficient heat to 'maintainthe :end 35'01 'switch arm 32 'in `eng'agenc.ent with contact36, thusvretaining the short circuit lacross the vglow switch I9 andfresistor43and effectively preventing theiluorescentlamp from starting,in asmuchas the vglow Vswitch starter is now :out of thecircuit. vlt-isapparentthatthe shortcircuiting of the -glow -switch starter I9 willoccur Aii" the lamp does noti-ight after -a'ffew cycles. Thus the rapid'destructionof Vthe Aglow switch t9, due to many repetitions of the`starting cycle cna defective lamp, is avoided. Shortly after thecircuit is broken by the `opening 'of switch I5, or opening of circuitby lamp removal, resistor 39 willcool'and allow'switch r32 to re-verttoits normal position shown in Fl-ig. 1, in readiness for normal operationwithareplacement lamp.

Resistor 43should have a relatively low `ohmic value, to have available.sufficient voltage across the opencontacts of `the `-glowswitch, toinitiate and maintain-the glow discharge. In the embodimentherein, a.Nichromedresstor is used, illustratively of in the order of 15 ohms,which will determine the desired current flow. However, as it onlyrequires a relatively small wattage to produce sufficient heat tomaintain the switch arm 32 in deected position, resistor 39 which in theembodiment herein is of carbon composition, should be of high ohmicvalue in the order of .20,000 .ohms clamore. Thus when-the-glow switch.starter and resistor 43 are short cii'cuited by switch arm 32 when thelamp is defective, and resistor 39 is placed across the electrodes IIand I2, resistor 39 will draw but little current and thus will use `but'little power.

Among other advantages of the circuit is the .fact .that the instant theswitch arm 32 disen- ,g'ages lcontact 37, 'the carbon resistor is cutinto circuit to become heated for the sal'ety action 'to commence. 'Thatsafety action is not interruptedfor an instant, but current evolvingeffective heat is passed through resistor 39 throughout the period thatswitch .arm 32 isin transit from contact 3? to contact't and thereafter.There is therefore no "danger of inhibiting the safety action on lowambient temperature as in a cold room for instance. 'Sufcient heat willbe developed by the heating of the carbon resistor 39 to ensure`positive movement of the switch varm vand to'guardagainstthe switch armfloating between 'contact arms '3? and 36, as it might if the .safetyaction ibegan only when switch arm 32 had been delle'cted'all the way'toasafety contact position.

Asafety starter unit incorporating Athe starting and safety controls ofthe circuit shown in Fig. l `and above described, is shown in Figs. 2 tov6 of the .drawingswherein the `numerals used in the circuit'diagram `ofFig. 'l are employed for corresponding elements. The unit which isconnected across leads ll' 4and I8 from electrodes IgI and I2respectively, comprises an insulating base 2`I `with two terminals '22and 23 depending therefrom Aand 'a metal cover or cap 24 .having tabsA25 removably to secure it to base 2l. The cap '24 had van )insulatingrliner 29 covering its side wall vand a yfurther insulating liner disk21 for its top wall. 'In the unit is enclosed the insulatingupstan'din'gpanel 28 4rigidly aflixed in the manner hereinafter setforth to terminal posts, 22 and 23 and having mounted on one sidethereof a starter I9 which preferably is of the glow switchtype.v'Thisswitch maybe of conventional construction, involving a. ,glasstube 29 filled 'with noble gas, such as neon for instance, and havingelectrodes 39 and 3l, one of which is U-s'h'ape'd and Lof bimetallicmaterial responsive to variations in temperature. The other components`of vthesafety starter unit are disposed on the 4side of panel'28opposed to the glow switch starter I9 and comprise a bimetallic switcharm 32, preferably lin the 'form of a leaf which is secured near thelupper end thereof to .panel 28 by the laterally extending .arm .33 ,ofa .metal clip`34, saidarmpressing'the end of switch arm 32 against thepanel. Clip 34 has tabs 35 unitary therewith extending through andbentover rigidly to affix cit `to .the Ipanel 28. The switch .arm 32Yextends vdownward the length of the vpanel and has a wire contact 35 atits end which .normally engages a contact bar 3l affixed atcne end Ibytabs .37 therefrom.

A Contact bar 36 .in juxtaposition fto Acontact bar 3.7 .and slightlyspaced therefrom, is affixed at one end tothe panel'by tabs 39 vandconnected to terminal .post 22. vContact bars 36 and .3-'I

straddle the wire Contact A35 of switch `arm 32. l

to said .panel and spacedl the wire contact 35 being normally inengagement with contact bar 31 and free to move between contact bars 36and 31. The said contacts are preferably of silver or silver plated forlow resistance and the inhibition of arcing.

Positioned alongside switch arm 32 is carbon resistor 39, one terminalwire 4|] of which is soldered to metal clip 34, while the oppositeterminal wire 4I is soldered to the tab end 31 of contact arm 31 andpasses through panel 28 to be connected to terminal 23 as at 42 toprovidea rigid support for one bottom corner of the panel.

Lead 41 of the glow switch starter I9 is soldered to the tab end 38 ofcontact arm 36 and passes through panel 28 to be connected to terminal22 as at 41' to provide a rigid support for the other bottom corner ofthe panel while lead 48 of the glow switch starter I9 extends through aneyelet 45 affixed to the panel at the top thereof.

' Positioned near the upper end of switch arm 32 is Nichrome resistor43, lead 46 thereof being soldered to metal clip 34 while lead 44thereof extends through eyelet 45 and is soldered thereat to lead 48 ofthe glow switch starter I9. It will be understood that the springtension of switch arm 32 is such as to maintain contact wire `35 thereofagainst contact arm 31 even at the highest temperature encountered inany place where a fluorescent lamp is normally installed or which isgenerated by the heat of a normally operating lamp. Thus it can be seenthat the control resistance 43 serves the double function of determiningthe voltage across the glow switch starter I9 and of initiating themovement of the thermal switch arm 32 in the repeated attempts to starta defective lamp. The safety resistance 39 thereby put in circuittogether with resistance 43 effectively move the thermal switch arm 32to contact arm 36 for short circuiting the starter unit and its controlresistance 43 and do so with a minimum of current which flowstherethrough as long as the defective lamp remains in circuit. 'Ihesystem and unit are therefore simple, economical or current andthoroughly reliable in action inasmuch as oating or hunting of thethermal switch arm 32 between its contact bars 36 and 31 is precluded,the thermal switch arm 32 remaining in its normal position as long asthe controlled lamp is in order and once it leaves contact bar 36 itmoves positively to the starter short circuiting position.

As many changes could be made in the above circuit and construction, andmany apparently widely different embodiments of this invention could bemade without departing from the scope of the claims, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes comprising a startingcircuit for passing current through said electrodes in series, saidcircuit comprising a pair of resistors connected in series between saidelectrodes, a thermally responsive switch arm in proximity to both ofsaid resistances and connected at one end therebetween, and a starter inthe series circuit between the connected end of said switch arm and oneof said electrodes, intermittently to interrupt said starting circuit,said switch arm becircuit across said safety resistor,

6 ing deflected by the heating of said resistors to short circuit saidstarter, thereby stopping the intermittent interruption of said startingcircuit.

2. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes comprising a startingcircuit for passing current through said electrodes in series, switchmeans intermittently to interrupt said starting circuit, a pair ofresistors in series with said switch means and said starting circuit,and a heat responsive switch arm normally short circuiting one of saidresistors, said switch arm being deilected by the heating of the secondof said resistors during the operation of said switch means to removethe short circuit from the iirst of said resistors and place the latterin the circuit, said switch arm being further deflected by the continuedoperation of said switch means to short circuit the second of saidresistors and said switch means, said first resistor evolving suiiicientheat to maintain said switch arm in denected position, thereby stoppingthe intermittent interruption of said starting circuit.

3. The circuit as claimed in claim 2 in which the means intermittentlyto interrupt said starting circuit comprises a starter of the glowswitch type.

4. In a safety starting and operating circuit for a gaseous electricdischarge device equipped with spaced electrodes, a starting circuit forpassing current in series between said electrodes, means automaticallyto interrupt said circuit to strike an arc between said electrodes andmeans to preclude the sustained intermittent starting of a defectivelamp, said latter means comprising a thermally operated switch armnormally in said starting circuit, a safety resistor in said startingcircuit normally short circuited by said switch arm, a control resistorin said starting circuit normally in series with said switch arm, saidswitch arm being deflected by the heat evolved in said control resistorin the attempted starting of a defective lamp to remove the short theheat evolved by said safety resistor in the continued attempted startingof a defective lamp deflecting said switch arm further to short circuitsaid control resistor and said means automatically to interrupt saidstarting circuit, thereby preventing further attempts to start saidlamp.

5. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes comprising a startingcircuit for passing current through said electrodes in series, a pair ofstarting contacts in said starting circuit, a pair of heater means insaid starting circuit, a heat responsive switch arm connected at one endbetween said pair of heater means and normally short circuiting one ofsaid heater means, the second of said heater means evolving suiiicientheat in the attempted starting of a defective lamp for displacement ofsaid switch arm to remove the short circuit across said first heatermeans, said first heater means evolving suicient heat in the continuedattempt to start said lamp to displace said switch arm' further to shortcircuit said second heater means and said pair of starting contacts,said iirst heater means maintaining said switch arm in displacedcondition as long as the circuit remains closed, thereby preventingfurther attempts to start said lamp.

6. A self contained safety starter unit for a gasecus electric device,said unit comprising a support base having a pair of terminal posts, aninsulating panel rising therefrom, an eyelet affixed to said panel, abi'metallic switch arm, a clip aiiixed to said panel and rigidlyclamping one end of said switch arm thereagainst, a wire contact lat thefree end of said switch arm, a pair of spaced contacts aiiixed to saidpanel in the path of movement of and straddling said wire contact, oneof said spaced contacts being normally engaged by said wire contact, aresistor positioned in Vclose heat transfer relation to said switch armat the aixed end thereof having one of its leads connected to said clipand the other `of its leads connected to said eyelet, a second resistorpositioned alongside said switch arm having one of its leads connectedto said normally engaged spaced con tact and to one of said terminalposts and the other of it leads aiiixed to said clip, a glow switchstarter having a pair of contacts, one of its con- .tacts beingconnected to the other of said terminal posts and to the other of saidspaced contacts, and the other contact of said starter being connectedto said eyelet.

'7. A panel unit for a safety starter unit, said panel unit having aglow switch starter on one side thereof having a pair of contacts, abimetal switch arm on the other side of said panel having a Contact end,a metal clip for said switch arm anixed to said panel and rigidlyholding one end of said switch arm thereto, a resistor having a pair ofleads and positioned in yclose heat transfer relation to the ailixed endof said switch arm, one of the leads from said resistor being connectedto said metal clip and the other lead from said resistor being connectedto one of the contacts of said starter, a contact bar affixed at one endto said panel and connected to the other contact of said starter, asecond contact bar also aiiiXed at one end to said panel and adjacent toand spaced from said iirst contact bar, said contact bars being in thepath of movement of said contact end, said contact end normally engagingsaid second contact bar and spaced from said iirst contact bar, acomposition resistor positioned alongside said switch arm and having apair of leads, one `of the leads being connected to said metal clip andthe other of said leads being vconnected to said second contact bar.

8. A safety starter unit for a gaseous electric discharge device havinga pair of spaced electrodes, said unit comprising a pair of terminals, avIbimetal switch arm, a support therefor at one end thereof, a `pair ofspaced contacts both in the path of movement of the outer end of saidswitch arm and straddling said outer end, one of said contacts beingnormally engaged by said outer end and the other of said contacts beingnormally spaced from said outer end, a pair of resistances each having apair of leads, said resistances being in close heat transfer relation tosaid switch arm, one of said resistances having a lower ohmic value thanthe other, one of the leads from veach of said resistances beingconnected to said switch arm, the other lead of the resistance of higherohmic value being connected to one of said terminals and to the normallyengaged contact, a. glow switch starter having a pair of contacts, oneof its contacts being connected to the vother end of the resistance oflower ohmic value and the -other of its contacts being connected to theother of said contacts of said pair of contacts and to the otherterminal.

9. In a starting and operating circuit for gaseous electric dischargedevices ,equipped with spaced electrodes, a starting circuit for passingcurrent through said electrodes in series, said starting circuitincluding a pair of starter contacts, means automatically to open saidcontacts when the arc across the electrodes is struck, and to maintainthem open while the arc exists, a thermally responsive arm in saidcircuit, a control resistor passing the starting current and generatingthe heat to deflect said arm to interrupt said starting circuit in theattempted starting of a defective lamp, a safety resistor normally outof circuit, said thermally actuated arm, when deiiected, connecting saidsafety resistor in `said starting circuit, said safety resistordeflecting'said arm further in the continued attempted starting of saiddefective lamp, and cutting said pair of starter contacts and saidcontrol resistor out of circuit, said safety resistor generatingsuiiicient heat to maintain said thermally responsive arm in deiiectedposition as long as the circuit remains closed.

10. The combination set forth in claim 9 in which said control resistorhas a low ohmic resistance of from 10 to 20 ohms and said safety re-lsistor has a relatively high ohmic resistance of from 20,000 to 50,000ohms.

IRWIN S. JACOBSEN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED vSTATES PATENTS

